Centrifugal machine.



No. 719,476. PATBNTED'FEB. 3, 1903.

J. LAIDLAW. CBNTRIPUGAL MACHINE.

APPLICATION FILED APB. 14, 1902.

UNTTED STATES PATENT OEEICE.

JOHN LAIDLAW, OF GLASGOW, SCOTLAND.

CENTRIFUGAL MACHINE.

SPECIFICATION forming part of Letters Patent No. l719,476, dated February 3, 1903. Application filed April 14, 1902. Serial No..102,853. (No model.)

T0 a/ZZ whom, t may concern.:

Beit known that I, JOHN LAIDLAW, of the firm of Watson, Laidlaw da Oo., engineers, of 9S Dundas street, South Glasgow, Scotland, have invented certain new and useful Improvements in Centrifugal Machines,of which the following is a specification.

This invention relates to an improvement in the construction of centrifugal machines which havea central opening in the bottom through which the dried material is discharged, with particular reference to the form of the bottom ofthe revolving basket. In some machines of this class the bottom extends only as far asis necessary to contain the material to be dried and slopes in a straight line right upto the shell or cylindrical part of the basket, the

angle of this Vslope being sufcient to allow` the dried materialto fall by its own weight when the machine is stopped. When treating materials such as sugar, for which this class of machine is principally used, the an-l gie of the slope is aboutforty-iive degrees (the angle of repose of the dry sugar in heap loose being about forty degreesrwith the horizontal,) or such an angle as will permit the dried material to slide downward by its own weight. It is well known that when freeing the sugar crystals from the residual mother-liquor in a centrifugal machine the perforated cylinder or shell. of the revolving basket must be lined with a suitable material which will allow the liquid to pass, but which will retain the sugar crystals. When the basket is full, the wall of sugar will rest upon the sloping bottom, and as the centrifugal action causes the liquid to pass through the sugar or other material radially and in a horizontal direction the liquid leaving that portion of sugar which is contained by the angle forming the sloping part of the bottom will have to How up the slope till it reaches the perforated shell or cylinder. In doing so the portion of the sugar lying on the slope is not so well dried unless the sloping part is covered with wire-gauze.

The object of this invention is to retain the benefit of the sloping bottom as far as possible without having to cover the conical bottom with wire-cloth or other material, which is somewhat difficult and expensive. This object is attained by making a part of the bottom of the revolving basket upon which the wall of material in the basket rests horizontal, or as nearly so as would allow the liquid to pass away freely, and the remaining portion of the bottom extending toward the center would have the requisite slope to permit the dried material to slide downward through the central opening by its own weight. The central opening will have the usual valve which slides up the spindle, and this valve is made to be fixed on the spindle, so as to be utilized as a distributer for the inflowing material when it is convenient to charge the basket while it is in motion. There will, however, be a portion of material remaining in the angle formed by the bottom and the shell of the basket which would have to be re-l moved by hand; but in practice it would :not be necessary to remove it every charge of the machine, as it would not oifer any hindrance tothe passageot the liquid.

In order that my invention may be properly understood and readily carried into effect, I have hereunto appended a drawing of a vertical section of a centrifugal machine.

In the'drawing, A is the basket and is shown with a vertical wall of sugar B,`which is the position the sugar takes up when the basket is revolving. In constructing the basket I make the outer part of the bottomC, on which the sugar rests, nearly horizontal, so as to allow the liquid to pass away freely through the perforated cylinder, and the remainder of the bottom D extending toward the center with requisite slope to allow the material to slide downward through the opening in the bottom of the basket by its own weight when the basket is stopped.

I claim- A centrifugal machine provided with a bottom formed with an outer part approximately horizontal for some distance from the side of the basket, equal to about the thickness of the vertical wall of the material contained, and a central part sloping at a greater angle than the outer part.

In testimony whereof I have hereunto affixed my signature in presence of two witnesses.

JOHN LAIDLAW.

Witnesses:

JOHN LIDDLE, AGNES MAoKINTosH.

IOO 

